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United States Patent Ofifi ce The present invention relates to new and useful compositions of matter and to the methods for their preparation. More particularly the present invention relates to new and useful temperature-stable, shock-stable, auto-- genetic gas-evolving compositions and methods for their preparation.

Many of the known autogenetic gas-evolving compositions of the present day are the result of mixing and blending rubbery organic materials with oxidizer-s. The

attendant dangers of such mixing and blending are then unduly multiplied by the necessity of extruding, molding and compacting of the flammable mixture to obtain the material in shapes such as stars, cylinders and the like which are useful in generating the necessary gas patterns for propulsion units. The heat produced by such Working, the power requirements of equipment capable of such working, and the instability of the materials being worked has contributed to and necessitated the development of expensive and tedious procedures to obtain even the simplest shapes. All of the inherent dangers attendant with the handling of explosive and combustible materials are present in these gas-evolving compositions and have been a contributing deterrent to commercial large scale low cost sources of this type of materials. It would therefore be advantageous to the art to have available a solid fuel-oxidizer autogenetic gas producing composition which needed no extensive or prolonged working; which in fact was stable well beyond the maximum temperature attained in any mixing or blending; which was liquid at room temperature during blending and therefore could be cast or poured into molds to shape; which has controlled water-solubility even when in the solid (cured) stage and which required little heat to solidify (polymerize).

The present invention provides just such an autogenetic gas-evolving, liquid pourable, temperature-stable, shockstable, heat-curable, water-soluble composition. The ad vantages of such are readily apparent to those skilled in the art.

The new compositions can be characterized as inorganic oxidizers intimately bound with polymeric materials having the general formula /m\ /n\ /a\ /p wherein A represents a monomeric or a recurring or repeating polymerized monomeric unit of a polymerizable material said monomeric unit having the general formula rho (i= ifizgiii i Fat-exited Mar. 1%, 19%54 monomeric unit of a polymerizable material different than A; r represents an integer from 0 to 2, inclusive; s represents an integer rom 0 to 1, inclusive; and, m, n, 0', and 12 represent integers such as to provide a polymer which has a Fikentscher K-v-alue of from 5 to 100. The Fikentscher K-value of a polymeric substance is a quantity, as defined by Fikentscher in Cellulosechemie, 13, 60 (1932), that represents an approximate measure of the weight fraction of a given sample of polymer in an infinitesimal molecular weight range. According to a concept that is widely acceptable to those skilled in the art, it may be in correlation, in an exponential manner, to the mean average molecular weight that obtains in a given sample of a polymeric substance. The K-value of a watersoluble polymer may be derived, in any given instance, by the formula:

wherein Z is the relative viscosity of a polymer solution at 1 percent by weight concentration in the solvent at any given temperature. For practical purposes, the same K values for any given water-soluble polymer may be determined according to the equation in US. 2,811,449. The new compositions prepared from the polymeric materials described above and an oxidizer are combustible, selfoontained autogenous evolvers of low-molecular weight gases having high thermal properties and thrust potential. These compositions are adaptable to be employed in ammunition and explosives as the powder or charge, and in power plants that convert thermal energy of a chemical reaction into high-energy streams of gas molecules. Thus, for example, the composition of the present invention can be used as the propellant in fixed ammunition or in bag-type ammunition. Further, the compositions can be employed as propellants in rockets, jet-assisted-take-oifs of airplanes, long-range or short-range missiles and in supersonic missiles, anti-aircraft missiles and in intermediate or short-range rockets, such as those fired from bazookas, and the like.

It has now been found that the composition comprising an inorganic oxidizer and as a fuel-binder a water-soluble polymeric product of the class consisting of homopolymers and copolymers of at least one monomer selected from the group of those having the general formulae:

log Z +0.001K

3 oxidizer composition. Thus, from the foregoing, it becomes apparent that a water-soluble polymeric fuel-binder can be prepared by homopolymerizin g a single species of one of the subgenera, represented by the Formulae I, 11

can also be copolyrnerized in the usual manner. Exemplary of materials of this class are those taught in our copending application Serial No. 791,279 and filed February 5, 1959, now abandoned. It is to be understood that and ill, above, or by copolymerizing two or more species 5 when the more insoluble ethylenically unsaturated mafrom the same or different subgenera. It is also to be terials above described are employed, usually no more understood that one or more of the monomers can be than percent by weight of the comonomer is employed copolymerized with substantially any other ethylenically if the water solubility of the polymerized product is to unsaturated polymerizable monomeric material. The be retained. latter material can be employed in varying amounts de- 10 In carrying out the present invention, the monomer pending upon its water-solubility and it has been found described above and represented by the Formulae I, II that generally up to about 10 percent by weight of such or III, alone or in admixture with the comonomer of the material can be included in the polymeric material Withseries represented by the Formulae I, II and HI and/or out impairing the usefulness of the ultimate polymeric an ethylenically unsaturated polymerizable monomer of composition. It is not to be inferred, however, that when a different series, is mixed with a solid inorganic oxidizthe different ethylenically unsaturated material is watering compound, such as, for example, boron hydride, a soluble per se that more than 10 percent by weight of solid peroxide, a nitrate or perchlorate of ammonia or a such cannot be employed. The polymerization of the nitrate or perchlorate of an alkali metal or the like. The monomeric mixture takes place readily at temperatures resulting mixture can be adjusted so as to form a slurry of from about 35 C. to about 200 C. The amount of for casting or a viscous mixture capable of extrusion. The oxidizer in the composition is widely variable since some mixture prior to polymerization is thus shaped and then gas production will occur when the polymeric composiheated at a. temperature of from about 35 to about 200 tion is ignited even when it contains little oxidizer. Thus C. to polymerize the polymerizable materials. The one can employ as little as 5 percent by weight of oxidizer monomeric materials are employed in an amount of from or as much as 90 percent by weight of oxidizer based on 5 to 90 percent, by Weight, based on the ultimate compothe ultimate composition. However, it is preferable to sition and preferable from 50 to 90 percent by weight. have from about 10 to 50 percent by weight of the inor- In any event the polymer-oxidizer material, either solid, ganic oxidizer in the ultimate composition. soft plastic, mass or slurry, is usually stable to heat and It is to be understood that other solid fuels, that is comlight up to about 300 C. without explosion. The new bustible materials which burn in a controllable manner polymer-oxidizer compositions can in some instances be such as the solid carbonaceous fuels as well as the inorremelted or softened and reformed without exploding. ganic fuels can be employed. By solid carbonaceous The polymeric material burns, on ignition, at an even, fuels we mean carbon-containing materials capable of slow rate when the percent organic polymer is high and at oxidation can be employed as well as solid organic maa fast, spurty rate when the percent organic polymer is terials containing surfur, oxygen and the like, such as low. The polymeric materials are in many instances Thiokol rubbers (Thiokol D, T hiokol 40, Thiokol A) and Water-soluble and can be dissolved in water to impregnate the like, if the end use requires somewhat higher heats of W t 'abie materials or, in case of accident or disposal even combustion. The inorganic fuels such as the alkaline those of sparing solubility, can be flushed with water, earth metal hydrides as well as the boron hydrides can be thus providing a S f easily hafidleabie ialused alone or in combination with the organic carbona- 40 The inorganic oxidizers which can be employed in acceous fuels. The monomer-oxidizer compositions of the Cordance With the present invention are the solid perprescnt invention are compatible with most solid fuel maoxides, nitrates and perchlorates Of ammonia OI the alkali terial and the presence of such fuels does not materially metals. Thus, for example, one can employ ammonium affect the technique of polymerization of the binder-fuel i ra mm perchlorate, potassium perchlorate, or reduce the rigidity of the ultimate polymeric composi- Sodium Perchloratfi, Sodium nitrate, Potassium nitrate, {i t i i th oxidizer, lithium nitrate, sodium peroxide, potassium peroxide and The monomer or monomers can be copolymerized with the like as well as mixtures of these with, for example, substantially other ethylenically unsaturated polymerizmagnesium hydride, boron hydride and the like, able materials. Representative of such materials (fuels) The following examples illustrate the present invention are the alkenyl aromatic hydrocarbons of the benzene but ar not tobe c n d a l mitingseries for example, such as styrene, divinylbenzene, the Examples isopropenyl benzenes, ethyl vinyl benzenes, the memopenyl toluenes, vinyltoluenes d h lik d h lk Polymerization of the below-listed materials was carried halides such as vinyl chloride, isopropenyl chloride and out at {he temperatums indicated Without eXplosiml t0 the like; and the acrylic acids and esters thereof and the Obtain a Product which could burned Produce large like, to alter the physical and chemical properties of the Volumes of gaseous p u The burning Characteraromatic polymer forapartioular application. Further Si iStiCS Were dfiterminfid y satul'ating a length of Cotton containing monomers which burn yet give a SiO matrix tring With an aqueous solution of the polymer product; which helps retain the shape of the burning solid fuel drying; and igniting.

Polymerization Properties of Product Shock Conditions Burning Char- Character- Ex. Monomer, Salt (0.1 acteristics of String istics N0. Gm. Gm.) Saturated with (Struck Time Temp, Appreaance Melting Char- Aqueous solution with Min. C. acteristics, 0. Hammer) 155-polymer ap- 1 0.01 V0 M N iNOL. 45 40 105..- Bea l s og s zglgsm ggzgfiggimgfl Bggn e d Stable.

gether with decomp polymer -po1yrner becoming soft. 170-melting 2 0.savo-1vr NH4NO3 32 50-100... Viscous solid g' .do D0.

280 gassing 292- more gas,

dark brown Polymerization Conditions Ex. Monomer,

Properties of Product Shook Burning Ohar- Characteractcristies of String istics Salt (0.1 No. Gm. Gm.)

Time

Temp. Min.

Appreaance Saturated with Melting Char- Aqueous solution aoteristics, 0. Hammer) 0.66 VO-M NH NO3 17 70405--- 0.02 VO-M NH C1O 14 63-105...

0.03 VO-M NH4ClO 15 50-105.

0.07 vo-M NHlNoa; 19

0.04 VO-M NH O1O4. 20 -105-..

0.06 VO-E NH4ClO 17 Brittle solid NH4C104- Viscous Solid Hard brittle solid.

Hard solid 170-melting 180-deoomp 285--no more gas ofr" Burned evenly Stable and slowly.

200dark brown 250 b1ack Burns spurty and a little less than l55- browning up.

Explodes.

mg. 185-fused, brown. 250E-very sl. gas

0 300b1ack char- 300-little change.

{195 ,melting Burns like No. 9.-

Very fast spurty burning.

Burns evenly and 300-deeomp slowly.

1 VO-M poly(vinyl-5-methyloxazolidinone).

2 VO polyvinyloxazolidinone.

8 VO-E poly(vinyl-5-ethyloxazolidinone).

The polymers per so have the following combustion enthalpy:

Calories per gram Polyvinyloxazolidinone 5290 Polyvinylmethyloxazolidinone 5740 Polyvtimyllethyloxazolidinone 6400 Further, the densities of the polymers of the present invention compare with the known fuels as illustrated in the following table.

Polymers of the present invention: Density at 20 to 25 C.

Polyvinyloxazolidinone 1.339 Polyvinylethylloxazolidinone 1.185 Polyvinylmethyloxaziolidinone 1.285

Other known fiuels:

Paraffins 0.85

Rubber (natural) 0.91 0 Thiokol D 1.34

Thiokol D4 1.39 Thiokol A 1.60

a Water-soluble polymer consisting of at least 90 percent by weight of a repeating unit having the formula Q. L (damn E2 .I

wherein X represents a member selected from the group consisting of -CH2-, -O-, and

each Y is independently selected nrom the group consisting of hydrogen, and lower alkyl radicals having from -1 to 4 carbon atoms, inclusive; r represents an integer from 0 to 2, inclusive; s represents an integer from 0 to 1, inclusive; said polymerization being carried out at a temperature between about 35 and 200 C.

2. A composition as in claim 1 wherein said inorganic oxidizer is ammonium nitrate.

3. A composition as in claim 1 wherein said inorganic oxidizer is ammonium perchlorate.

4. A composition as in claim 1 wherein said fuelbinder is polyvinyloxazolidinone.

5. A compound as in claim 1 wherein said fuel-binder is polyvinylethylloxazolidinone.

6. A compound as in claim 1 wherein said fuel-binder is polyvinylmethyloxazolidinone.

References Cited in the file of this patent UNITED STATES PATENTS 2,818,362 Dreschel Dec. 31, 1957 2,818,399 Dreschel Dec. 31, 1957 2,919,279 Walles et a1. Dec. 29, 1959 2,948,656 Tousignant et a1. Aug. 9, 1960 2,992,908 Hedrick et a1. July 18, 1961 

1. A SOLID ROCKET FUEL COMPOSITION COMPRISING A SOLID INORGANIC OXIDIZING AGENT AND CONTAINING AS A FUEL-BINDER A WATER-SOLUBLE POLYMER CONSISTING OF AT LEAST 90 PERCENT BY WEIGHT OF A REPEATING UNIT HAVING THE FORMULA 